1. Field of the Invention
The present invention relates to a protecting agent supplying member, a protective layer forming device, and an image forming apparatus.
2. Description of the Background
Regardless of a developing system for use, an image forming apparatus of a conventional electrophotographic system generally uniformly charges its image bearing member (commonly referred to as a photoconductor), generally in the shape of a drum or a belt, while rotating the image bearing member, forms a latent image pattern on the image bearing member using laser light or the like, and making the latent image visualize to form a visible image by its developing device, and transfers the visible image (a toner image) to a transfer medium to form an image.
Some toner residuals, which have not been transferred, remain on the image bearing member after transferring the toner image to the transfer medium. If the image bearing member is subjected to the charging process with bearing such residuals, the residuals impair the uniform charging of the image bearing member. Therefore, it is common that the toner residuals or the like remained on the image bearing member is removed in a cleaning step, after the transferring step, and the charging is performed in the state where the surface of the image bearing member has been sufficiently cleaned.
In each step of the image formation, there are various physical stress and electric stress. The image bearing member that has received the various physical stress or electric stress changes its surface condition as time passes.
For example, it has been known that, among the stress mentioned above, the stress caused by the friction in the cleaning step abrades the image bearing member, and gives scratches on the image bearing member.
To solve the problem as mentioned, it has been known that it is effective to apply a protecting agent onto the image bearing member. With the application of the protecting agent onto the image bearing member, the friction coefficient of the surface of the image bearing member reduces, which inhibits the deterioration of a cleaning blade or the image bearing member, and the releasing ability of the depositions, such as toner residuals from the transferring, on the image bearing member is improved, which can prevent cleaning failure occur in time, or prevent occurrences of filming.
There is disclosed, as a technique for applying a protecting agent onto an image bearing member, a protective layer forming device containing a protecting agent block, a protecting agent supplying member formed of a rotatable brush member configured to be in contact with the protecting agent block and to apply the protecting agent bearing thereon to the image bearing member, and a protecting agent pressing member configured to press the protecting agent block to thereby bring the protecting agent block into contact with the protecting agent supplying member (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2007-65100).
In this proposed technique, however, a large amount of the powder of the protecting agent scraped from the protecting agent block by the rotation of the rotatable brush member is scattered, which generates a large amount of the waste of the protecting agent. Moreover, since the brush fibers collapse or are deteriorated with time, the consumption amount of the protecting agent is not stable, and therefore it may not be able to supply a constant amount of the protecting agent for a long period of time.
To encounter this problem, there is disclosed a technique using, as a protecting agent supplying member of a protective layer forming device, a protecting agent supplying member which has a foam layer and is in the form of a roller (see, for example, JP-A No. 2009-150986). In accordance with this proposed technique, scattering of the protecting agent powder due to the abrasion hardly occurs.
However, in this technique, the protecting agent supplying member, which has a foam layer and is in the form of a roller, is soft and thus the force thereof for scraping the protecting agent block is small. As a result, the protecting agent cannot be sufficiently supplied to the image bearing member, and it may be difficult to sufficiently prevent filming of the image bearing member. If the amount of the protecting agent block scraped by the protecting agent supplying member is attempted to increase by pressing the protecting agent block at high pressure, large load is applied to protecting agent block and the protecting agent block is not evenly scraped in the length direction, which cause the variation in the supplied amount of the protecting agent in the length direction of the protecting agent block. As a result, there is no protection effect of the protecting agent on the portion of the image bearing member where the supplied amount of the protecting agent is small, and filming occurs on such portion.
Accordingly, it is current situation that a protecting agent supplying member, which has a foam layer, is in the form of a roller, is capable of reducing the scattering of the protecting agent powder generated by abrasion, does not need use a large amount of the protecting agent, and is capable of preventing filming, is desired, as well as a protective layer forming device and image forming apparatus using the protecting agent supplying member as described.